1. Technical Field
The present invention relates to an airbag device for protecting an occupant such as a driver and a passenger in a vehicle against an impact due to a side collision, the vehicle having seats disposed apart from each other in a vehicle width direction.
2. Related Art
A method has been widely used in which an airbag device provided in a vehicle is activated to reduce an impact to an occupant when a collision of the vehicle occurs. A conventional airbag device is disposed in a steering wheel provided forward of the driver's seat or in an instrument panel provided forward of a front passenger seat so that forward movement of an occupant facing the airbag device is restrained. Thus, an impact to the occupant at the time of a head-on collision of a vehicle is reduced and the occupant may be protected from the head-on collision.
In recent years, a device has been developed that protects an occupant using an airbag device even at the time of a side collision of a vehicle. For example, what is called a side airbag device inflates between the side (door) of a vehicle body and the occupant to protect the occupant. Thus, the occupant is protected against a direct impact in a side collision of a vehicle as well as prevented from colliding with the side of the vehicle.
Such a conventional side airbag device is unable to restrain inward movement of the occupant in a vehicle width direction. For this reason, when a side collision of a vehicle occurs, the occupants on the driver's seat and the adjacent front passenger seat may collide with each other, or the occupants may collide with the backrest of the adjacent seat. In order to address such problems, an airbag device described in Japanese Unexamined Patent Application Publication (JP-A) No. 2010-115947 allows an airbag to expand upward, the airbag being housed in a center console provided between the driver's seat and the adjacent front passenger seat. Thus, the airbag expands between the driver's seat and the front passenger seat, thereby making it possible to prevent collision between a driver on the driver's seat and a passenger on the front passenger seat. When a passenger is on the front passenger seat, the airbag is supported by the passenger in the vehicle width direction. On the other hand, when a passenger is not on the front passenger seat, the airbag fills a space over the front passenger seat, the space facing the driver on the driver's seat, and the airbag is supported by the door near the front passenger seat. Thus, the expanded airbag is able to provide a reaction force for receiving an impact force in the vehicle width direction, and movement of the driver on the driver's seat toward the front passenger seat may be efficiently restrained.
The airbag of the airbag device described in JP-A No. 2010-115947 is caused to expand in an I-shape as viewed from the front, and thus when the upper half body of an occupant is moved inwardly in the vehicle width direction in the case of a side collision of a vehicle, the shoulder of the occupant first comes into contact with the airbag. Therefore, although inward movement of the shoulder of the occupant in a vehicle width direction is restrained, it is difficult to restrain inward movement of the neck of the occupant in the vehicle width direction. To cope with this, a depressed portion may be formed on a face of the airbag, which is to be contact with the shoulder of the occupant, so that the shoulder and neck of the occupant come into contact with the airbag simultaneously.
However, occupants may have a difference in body size. In particular adults and children have a large body size difference. For this reason, when a depressed portion is formed on an area of the airbag, which is to be contact with the shoulder of an occupant, the depressed portion may be near the head of a small occupant such as a child. In such a situation, in the case of a side collision of a vehicle, there is a possibility that the head or upper half body of a child may be caught in the depressed portion of the airbag.